An engine of a vehicle may be automatically stopped without a human driver providing input to a device that has a sole purpose or function of stopping engine rotation to conserve fuel. The engine may be automatically restarted in response to an increase in driver demand torque, release of a brake pedal, low battery charge, or other conditions. The conditions that trigger an automatic engine restart may allow the engine to be restarted so that the battery may be recharged and so that engine torque may be provided to the vehicle's driveline, but automatic engine starting may influence other vehicle systems in ways that may be less than desirable. Therefore, it may be desirable to provide a way of automatically restarting an engine that may have less influence on other vehicle systems.
The inventors herein have recognized some dis-advantages of automatic engine restarting and have developed a method for operating an engine, comprising: automatically stopping an engine via a controller; and via the controller, inhibiting automatic starting of the engine while changing from a first driveline wheel mode to a second driveline wheel mode.
By inhibiting automatic starting of an engine while changing from a first driveline wheel mode to a second driveline wheel mode, it may be possible to provide the technical result of improved automatic engine starting. For example, if a vehicle operator is attempting to change from a two wheel drive mode to a four wheel drive mode, automatic engine starting may be inhibited until the driveline wheel mode change is complete. This allows the driveline wheel mode to be completely engaged before the engine is automatically restarted so that battery voltage is high enough to complete the driveline wheel mode engagement. After the driveline wheel mode is completely engaged, the engine may be automatically started. On the other hand, if the engine is in the process of automatically starting and a driveline wheel mode is requested, engagement of the driveline wheel mode may be delayed until the engine starting is complete so that the driveline wheel mode may be completely engaged.
The present description may provide several advantages. In particular, the approach may improve driveline wheel mode engagement. In addition, the approach may reduce the possibility of driveline wheel mode actuator degradation. Further, under some conditions, the approach may improve vehicle launches by fully engaging a driveline wheel mode before vehicle launch.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.